An adjustable, Set 7 bearing is a needlessly complicated design that weakens the differential:

The bearing is flipped around backward, so the race is captive between it and the axle flange. This means the bearing must float in the housing end and requires an adjuster, thrust block or thrust pin. Of course, an adjuster, thrust block or thrust pin must pass through the center of the differential. A hole drilled in the cross shaft of a 4 pinion carrier creates a stress riser that is prone to breaking. A 2 pinon carrier allows the thrust block to pass around it unobstructed, but the 2 pinion design also limits the differential's strength.

Limits side gear spline engagement:

Axle spline engagement also suffers because the width of the thrust block (which must have room to slide side to side) protrudes into the splined area of the side gears. This limits spline engagement in differentials with a 2 piece cone or clutch-hub/side gear arrangement.

Is prone to leakage and dirt/water contamination in many applications:

Beaded steel and foam gaskets don't keep water from running into the housing end and into the non-sealed wheel bearing. Don't forget to check your A7 wheel bearings if you ever back a boat into the water.

Axle flange stand-out is not held constant unless you blueprint the axle lengths:

Measure the axle flange stand-out on both sides of any stock 8 3/4" rearend. Because of production tolerances, a single adjuster causes the axle flange to stick out farther on 1 side than the other. The length of both axles, and the housing width is critically dependont on each other. Because everyone uses tape measurements to specify axle and housing lengths, making a set of axles with adjustable set 7 wheel bearings for a custom application is very hard. Axle flange standout varies greatly unless the axles are cut long, installed then blue printed to length.

Most of these problems could have been avoided if the "engineer" who designed the system would have flipped the bearings around so the race would seat against a machined step inside the housing end. This would require no adjustment, no thrust buttons and the axle lengths wouldn't be critical.

I thought about making special billet housing ends that would accept non adjustable set 7 tapered wheel bearings. Then I realized the design wouldn't sell because there is really nothing wrong with snap-ring style Green bearings.

Green bearings make my life easier. I sell at least 500 a year, and my customer's rarely have problems with them. In contrast, almost every time I sell set 7 bearings, the customer has installation questions/problems.